Within the theory of ion channeling in single crystals the so-called rule of reversibility claims equal probabilities for de- and rechanneling. However, the experimental study of this work shows a strong violation of this rule. Specially developed computer simulations provide the explanation of this unexpected behavior in terms of a hysteresis o...

The particle beam self-modulation instability in tapered and inhomogeneous plasmas is analyzed via an evolution equation for the beam radius. For a sufficiently fast taper the instability is suppressed, and the condition for growth suppression is derived. The form of the taper to phase lock a trailing witness bunch in the plasma wave driven by a...

The particle beam self-modulation instability in tapered and inhomogeneous plasmas is analyzed via an evolution equation for the beam radius. For a sufficiently fast taper the instability is suppressed, and the condition for growth suppression is derived. The form of the taper to phase lock a trailing witness bunch in the plasma wave driven by a self-modulated beam is determined, which can increase the energy gain by several orders of magnitude. Growth of the instability places stringent constraints on the initial background plasma density fluctuations. Minimize

A long, relativistic particle beam propagating in an overdense plasma is subject to the self-modulation instability. This instability is analyzed and the growth rate is calculated, including the phase relation. The phase velocity of the wake is shown to be significantly less than the beam velocity. These results indicate that the energy gain of ...

A long, relativistic particle beam propagating in an overdense plasma is subject to the self-modulation instability. This instability is analyzed and the growth rate is calculated, including the phase relation. The phase velocity of the wake is shown to be significantly less than the beam velocity. These results indicate that the energy gain of a plasma accelerator driven by a self-modulated beam will be severely limited by dephasing. In the long-beam, strongly-coupled regime, dephasing is reached in a homogeneous plasma in less than four e-foldings, independent of beam-plasma parameters. Minimize

REGAE (Relativistic Electron Gun for Atomic Exploration) at DESY in Hamburg is a linear accelerator for electron diffraction experiments. It is upgraded to allow for laser driven wake field accelerator experiments. The bunch length is around 10 fs and the wakefield structure is about 100 fs and the synchronization of the laser and the electron b...

REGAE (Relativistic Electron Gun for Atomic Exploration) at DESY in Hamburg is a linear accelerator for electron diffraction experiments. It is upgraded to allow for laser driven wake field accelerator experiments. The bunch length is around 10 fs and the wakefield structure is about 100 fs and the synchronization of the laser and the electron bunch needs to be in order of the bunch length. To achieve this, a RFbased scheme will be used, comparing the phase of a beam induced signal with the reference clock. To improve the performance for the operation with charges well below 1 pC a beam arrival time cavity (BAC) at 3.025 GHz is foreseen as a highly sensitive pickup. To provide the maximum energy to the measurement electronics, the cavity needs a high R=Qvalue and an optimized coupling. An over-coupled setting might be beneficial as it provides a higher signal-to-noise ratio for the first samples. In this paper the concept of the beam arrival time cavity, the influence of the dark current on the measurement and parameter studies and optimization of the cavity itself are presented. Minimize

Recent epidemiological observations suggest that clinical evolution of Plasmodium falciparum infections might be influenced by the concurrent presence of another Plasmodium species, and such mixed-species infections are now known to occur frequently in residents of most areas of endemicity. We used mice infected with P. berghei ANKA (PbA), a mod...

Recent epidemiological observations suggest that clinical evolution of Plasmodium falciparum infections might be influenced by the concurrent presence of another Plasmodium species, and such mixed-species infections are now known to occur frequently in residents of most areas of endemicity. We used mice infected with P. berghei ANKA (PbA), a model for cerebral malaria (CM), to investigate the influence of experimental mixed-species infections on the expression of this pathology. Remarkably, the development of CM was completely inhibited by the simultaneous presence of P. yoelii yoelii but not that of P. vinckei or another line of P. berghei. In the protected coinfected mice, the accumulation of CD8+ T cells in the brain vasculature, a pivotal step in CM pathogenesis, was found to be abolished. Protection from CM was further found to be associated with species-specific suppression of PbA multiplication. These observations establish the concept of mixed Plasmodium species infections as potential modulators of pathology and open novel avenues to investigate mechanisms implicated in the pathogenesis of malaria. Minimize

A longitudinal space charge amplifier (LSCA), operating in VUV anmd soft x-ray regime, was recently proposed. Such an amplifier consists of a few amplification cascades (focusing channel and chicane) and a short radiator undulator in the end. The amplification mechanism is broadband and robust, it is practically insensitive to energy chirp and o...

A dedicated accelerator research and development facility SINBAD (Short INnovative Bunches and Accelerators atDESY) is proposed. This multi-purpose research facility is initially aimed at promoting three major goals: (1) Shortelectron bunches for ultra-fast science. (2) Construction of a plasma accelerator module with useable beam quality(3) Set...

A dedicated accelerator research and development facility SINBAD (Short INnovative Bunches and Accelerators atDESY) is proposed. This multi-purpose research facility is initially aimed at promoting three major goals: (1) Shortelectron bunches for ultra-fast science. (2) Construction of a plasma accelerator module with useable beam quality(3) Setup of an attosecond radiation source with advanced technology. Research and development on these topics ispresently ongoing at various places at DESY, as add-on experiments at operational facilities. The two research goalsare intimately connected: short bunches and precise femtosecond timing are requirements for developing a plasmaaccelerator module with external injection or staging. The scientific case of a dedicated facility for accelerator researchat DESY is discussed. Further options are mentioned, like the use of a 1 GeV beam from Linac II for FEL studies. Thepresently planned conversion of the DORIS accelerator and its central halls into the SINBAD facility is described. Theavailable space will allow setting up several independent experiments with a cost-effective use of the same infrastructure(for example a central high power laser, a central timing and synchronization lab, etc.). National and international contributions and proposals can be envisaged. A preliminary, possible layout and the design work plan are discussed. Minimize